Snap action device



Dec. 14, 1954 H. wlNET SNAP ACTION DEVICE Filed Oct. 2, 1951 /N v /v TORHANS W/NET ATTORNEYS.

United States Patent SNAP ACTION DEVICE Hans Winet, Zurich-Wollishofcn,.Switzerland; assignor to Landisc Gyr, A. G., a bodycorporateof'switzerland Application ctober 2, 1951, Serial No. 249,272

Claims priority, application Switzerland April 26, 1951 7 Claims.((31.200-67) The present invention is a snap action device particularlyas-adapted to-be usedin electric switches.

Objects and advantages of the invention will beset forth inparthereinafter and inpart will be obvious herefrom, ormay be learnedby'practice' with the invention, the same being realized andattained bymeans: of the inst-rurnentalitiespointedoutin the appended claims:

The invention consists in the novel parts, constructions, arrangements,combinations and improvements herein shownv and' described.

An object of the invention is to provide a novel snap action devicewhich can be made from a single blank cheaply and easily.

A further object of the invention is to provide a novel snap actiondevice which can readily be adapted to be used with electric switches,and similar devices.

The accompanying drawings, referred to herein and constituting a parthereof, illustrate one embodiment of the invention, and together withthe description, serve to explain the principles of the invention.

In the drawings:

Fig. l is a front sectional view showing the novel snap action devicemounted in a tumbler switch with the snap action device shown in itsnormal position of rest.

Figs. 2-4 are front elevational views of the snap action device in atumbler switch in various operative positions. Fig. 4 illustrates theabnormal position in contrast to Fig. l, the normal or resting position.

Fig. 5 is a top plan view of the novel snap action device.

Fig. 6 is a sectional view of the embodiment shown in Fig. 5, as viewedalong line 66.

Fig. 7 is a side elevational view of the embodiment shown in Fig. 5.

Figs. 8 to are diagrammatic representations of the trip spring in theoperative positions illustrated in Figs. l-3.

As shown in Fig. 1, the snap action device is mounted in a tumblerswitch, said tumbler switch consisting of a mounting plate 1 made ofinsulating material, a contact 2, a housing cover 3, a second contact 4and a switching member 5. The switching member 5 is operativelyconnected to the novel snap action device. The snap action device ismade from a single blank and is in the form of a spring. The snap actiondevice or spring is positioned in the housing formed by the mountingplate 1 and the cover 3, said spring locally fixed at two points a, a toa base piece 6, the base piece 6 having the shape of a U (Figs. l-4)formed within a plane (as shown by the dotted lines of Fig. 7). Thespring may be fixed, for example, by welding with the U-shaped planeplate 6 having pro ections 8-8 on which washers 9, 9' are mounted. Thesnap action device or spring consists of two longitudinal stiffenedmembers 10 and 11 connected integrally by end members 12 and 13. Endmember 12 has an aperture 14 adapted to receive a contact 15. Themembers 10 and 11 are stiffened by means of bendingover operationseffected on the outwardly directed edges of said parts to form lips 10aand 11a. Elastically deformable U-shaped sections 16 and 17 are formednear the right end of stiffening members 10 and 11 by merely bendingsaid members in the shape of a U out of the plane of said stiffenedmembers. From the left station ary point a, there passes to the rightanother stittfened member 18, the stiffening of which is brought aboutby stamping it in the shape of a trough 19. Two compression spring parts20 and 21 are connected at their left "ice 2 end to end member 12 a nrlat their: right end to stiffened member 18. In making the-spring,the-spring is stamped out of an elastic pieceof sheet such: as bronzesheet. "Fl-remembers 20 and 2 1' must be bent'upwardly when the: springistmount'ed in the plate: 6 so that? said members 20 and 21 can serveafterwards as compression springs.

Figs. 8 to 10', the diagrammatic illustrations of the spring, have beenin'cl-uded in: order to show the forces actingon the spring when in use.In the position of. rest shown in Fig. 8, a turning moment M1 acts in a;counterclockwise direction on the stiffened members 10 and 1 1:" whichare connected at their left end by the end member 12 carrying: theContact" 15, which turning moment produces a comparatively large.pressure between contacts 2- and 15. If a definite actuating pressurevDo acts on the stiffened member 18, said member 18! is swung in aclockwise direction. This in turn causes-the right end of member 18 todrop thu'sdecreasing the turn-- ing moment M-i. As can be seen in Fig.9, after the" right end of stiffened member 1 8has dropped to a certain'point, the compressive force of the members 28 and 21 now acts in: theplane of the: stiffened members. It) and 1 1. slight additional increaseof the. actuating pressure Db tb lD1 produces: a small shift of thestiffened member 18 which causes the spring to trip. As can be seen inFig. 10, the turning moment now acts in the clockwise direction on thestiflfened members 10 and 11. In order to return the switch to itsoriginal contact position, the pressure on the switching member 5 mustbe reduced from D1 to (D2D1). By moving the parts 2 and 4, it is alsopossible to cause the spring to trip by means of an actuating pressurein the opposite direction.

As can be seen from the relative shapes of members 16 and 17 in Figs.l-4, the forces of different magnitude acting in the longitudinaldirection of tension members 10, 11 cause the elastically deformablemembers 16 and 17 to change their shape so that contact 15 executes arelative motion in the horizontal direction. This has the double featurein that, first, a self-cleaning effect of the contact surfaces isobtained and secondly, contact weldings that have occurred are removed.

The snap action device or spring of this invention has many otherdesirable features. Since no knife edges are used as part of the device,the spring remains practically free of friction since no frictionsurfaces are present and only variations of internal strain appear atthe bearing points. Changes in stress of the spring in consequence ofwear of bearings are therefore out of question. The flexure ofcompression members 20 and 21 is not critical, as according to Euler thepower of reaction of a leaf spring subjected to buckling stress remainsalmost constant for small flexures within the elastic limit, incontradistinction to the conditions obtained with regard to helicalsprings. This olfers the advantage that the making and mounting of thespring is greatly facilitated as no narrow tolerances must be observed.For the same reasons, no adjusting members for the pressure of thespring are necessary. The electric current carrying capacity of thecurrent carrying spring is comparatively great as no unsafe points inknife edge bearings need be taken into consideration.

As mentioned previously the spring may be stamped from a single blankwhich makes its production very cheap. No support members forcompression members 20 and 21 are required and it is obvious that it isrelatively simple to mount the spring when in use.

The invention in its broader aspects is not limited to the specificcombinations and improvements described but departures may be madetherefrom within the scope of the accompanying claims without departingfrom the principles of the invention and without sacrificing its chiefadvantages.

I claim: I

1. A snap action device made from a single blank of metal comprising twosymmetrically arranged spring members acting as compression springs,said members being disposed between two stiffened members, saidstiffened members being stationary at one end and connected to eachother at the other end by means of a contact carrying member, each ofsaid stiffened members having an elastically deformable section, and athird stiffened member located, between said symmetrically arrangedspring members and being stationary at the opposite end at which saidabove two stitfened members are stationary, said third stiffened memberbeing free at its other end and serving as an actuating member.

2. A snap action device as defined in claim 1, in which the elasticallydeformable section of the two stiffened members is U-shaped section bentout of the plane of the snap action device.

3. A snap action device as defined in claim 1 in which the stationaryends of the three stiffened members are supported on the outer legs of aU-shaped plane base piece.

4. A snap action device as defined in claim 3 in which the stationaryends of the three stitfened members are welded to the legs of the planebase piece.

5. A snap action device made from a single blank of metal comprising abase piece, two stiffened members connected one to the other at one endby a connecting member fixedly mounted on said base piece and at theother end by a contact carrying member, each of said stiffened membershaving an elastically deformable bulge projecting from the plane of thestiffened member adjacent its mounted end, two symmetrically arrangedspring members disposed between said stiffened members and acting ascompression springs, said spring members connected at one of their endsto said contact carrying member and connected at their other end to athird stiffened member, said third stiffened member disposed betweensaid spring members and fixedly mounted on said base piece at its endopposite it its end connected to said spring members, whereby said thirdstiffened member is an actuator.

6. A snap action device as defined in claim 5 characterized by the factthat the outer longitudinal edges of the first mentioned two stiffenedmembers are bent over to increase the stiffening effect.

7. A snap action device as defined in claim 6 characterized by the factthat the third stiffened member is stamped with a longitudinallyextending trough whereby the stiffening effect is increased.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date Re. 23,412 Hollis Sept. 25, 1951 2,170,748 Eaton Aug. 22, 19392,246,581 Fetter June 24, 1941 2,404,874 Wohl July 30, 1946 2,476,045Kaminky July 12, 1949 2,508,040 Ransome May 16, 1950 2,565,790 Van Ryanet a1. Aug. 28, 1951 2,571,453 Jackson Oct. 16, 1951 2,589,463 MillerMar. 18, 1952

